1. The Field of the Invention
The present invention relates to airbag inflation systems in motor vehicles. More specifically, the invention relates to an airbag diffusion system for diffusing inflation gases exiting a curtain airbag inflator.
2. Technical Background
Inflatable airbags are well accepted for use in motor vehicles and have been credited with preventing numerous deaths and injuries. Some statistics estimate that frontal airbags reduce the fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Statistics further suggest that with a combination of seat belt and airbag, serious chest injuries in frontal collisions can be reduced by 65% and serious head injuries by up to 75%. Airbag use presents clear benefits and vehicle owners are frequently willing to pay the added expense for airbags.
A modern airbag apparatus may include an electronic control unit (ECU) and one or more airbag modules. The ECU is usually installed in the middle of an automobile, between the passenger and engine compartments. If the vehicle has a driver airbag only, the ECU may be mounted in the steering wheel. The ECU includes a sensor which continuously monitors the acceleration and deceleration of the vehicle and sends this information to a processor which processes an algorithm to determine if the vehicle is in an accident situation.
When the processor determines that there is an accident situation, the ECU transmits an electrical current to an initiator in the airbag module. The initiator triggers operation of the inflator or gas generator which, in some embodiments, uses a combination of compressed gas and solid fuel. The inflator inflates a textile airbag to impact a passenger and prevent injury to the passenger. In some airbag apparatuses, the airbag may be fully inflated within 58 thousandths of a second and deflated within two tenths of a second.
An airbag cover, also called a trim cover panel, covers a compartment containing the airbag module and may reside on a steering wheel, dashboard, vehicle door, along a vehicle roof rail, vehicle wall, or beneath the dash board. The airbag cover is typically made of a rigid plastic and may be forced open by the pressure from the deploying airbag. In deploying the airbag, it is preferable to retain the airbag cover to prevent the airbag cover from flying loose in the passenger compartment. If the airbag cover freely moves into the passenger compartment, it may injure a passenger.
Airbag apparatuses have been primarily designed for deployment in front of the torso of an occupant between the upper torso of an occupant and the windshield or instrument panel. Conventional airbags, such as driver""s or passenger airbags (hereinafter referenced as the xe2x80x9cprimary airbagxe2x80x9d), protect the occupant""s upper torso and head from colliding with a windshield or instrument panel.
Airbag technology has advanced to include airbag apparatuses which protect occupants during a side impact, or roll-over accident. Airbags are used in other areas of the vehicle as well. Knee airbags exist to position and stop movement of an occupants knees and legs. Shoulder restraint airbags exist to push the occupant back into the seat to prevent injury from slack which may exist in the shoulder restraint.
Recent technological advances and uses for airbags has greatly increased their use and application. These airbag applications are common in that they generally include an inflator. The inflator, once triggered, uses compressed gas, solid fuel, or their combination to produce rapidly expanding gas to inflate the airbag. The inflator may be installed within the airbag, or otherwise operably connected to the airbag such that gas generated by the inflator inflates the airbag during an accident.
Airbags which inflate between the occupant and a side of the vehicle are known as curtain airbags. The curtain airbag inflates and descends to cover a vehicle window or side-wall like a curtain. Curtain airbags are becoming more popular. In side impact accidents the occupant may be thrown against the windows, doors and side-walls of the vehicle. The curtain airbag may protect an occupant from impact with a side window, flying shards of glass, side interior components, and other projectiles. The curtain airbag may also help to keep the occupant inside the vehicle during a roll-over accident.
Generally, the curtain airbag is attached to a long thin frame member which runs along a side of the roof of the vehicle. Often due to window size and visibility requirements, the curtain airbag apparatus has a long thin shape corresponding to the frame member. The curtain airbag inflates and descends from the frame member to cover a majority of the area between the occupant and the side of the vehicle interior.
The size requirements placed on the curtain airbag apparatus are reflected in the inflator installed within the textile airbag. The inflator may be generally long and thin in shape. The inflator is also generally rigid such that inflation gas is properly directed through the inflator and out into the airbag through exit ports in the inflator. The inflator is generally one of the few rigid components of the curtain airbag apparatus. Therefore, the size of the inflator generally dictates the size of the curtain airbag apparatus.
To provide sufficient inflation gas and to fill the airbag in the desired manner, a curtain airbag inflator generally extends a significant portion of the length of the airbag at a central location within the airbag. Exit ports disposed along the length of the inflator fill the airbag in a desirable manner. The central location and length of the inflator provides for quick and even inflation of the airbag.
As mentioned above, the curtain airbag apparatus is generally mounted to a side roof frame member (herein referred to as a xe2x80x98roof railxe2x80x99). The roof rail is generally shaped to follow the contour of the vehicle roof. Generally, due to aesthetic and aerodynamic factors the vehicle roof rail is curved to some degree. This requires that the curtain airbag apparatus and its components also curve to follow the contour of the vehicle roof.
Conventionally, a curtain airbag apparatus is designed and sized to fit properly within a particular make and/or model of vehicle. The confined installation area of the roof rail for the curtain airbag apparatus requires that differences between roof contours of a particular model or make of vehicle require a different shaped and sized curtain airbag apparatus. The different shaped and sized curtain airbag apparatus requires that the inflator be fabricated to different sizes. Fabricating inflators of different sizes requires down-time and re-tooling to adjust fabrication machines to produce the different size inflators.
Generally, the cross-sectional shape of the inflator is not changed to accommodate differences in roof rails between vehicles. The inflator is preferably cylindrical in shape. Inflators are generally made of metal. The cylindrical shape is simple to form. A cylindrical shape is preferable because ignition of gas generant within the inflator causes the inflation gas to expand in all directions. A cylindrical shape helps guide the inflation gas evenly through the inflator and out the exit ports.
The width of the roof rail generally has minimum requirements which are set to ensure vehicle structural integrity and safety. Therefore, the diameter of the cylindrical inflator generally remains unchanged. Alternatively, where a wider roof rail is used the diameter of the inflator may be increased.
Therefore, in order for the curtain airbag apparatus to properly function on a wide variety of vehicles having various roof contours, the designers conventionally are limited to changing the length of the curtain airbag apparatus which varies the length of the inflator. This may result in a plurality of curtain airbag apparatuses installed on one side of the vehicle. Additionally, each curtain airbag may require a different length inflator. As indicated above, this increases fabrication costs.
Accordingly, it would be an advancement in the art to provide a modular curtain airbag inflator which is comprised of modular sections. It would be a further advancement to provide a modular curtain airbag inflator which allows the modular sections to be connected to create different length curtain airbag inflators. Additionally, it would be an advancement in the art to provide a modular curtain airbag inflator which curves to follow a contour of a vehicle roof. The present invention provides these advancements in a novel and useful way.
The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available curtain airbag inflators. Thus, the present invention provides a modular curtain airbag inflator which allows various inflator lengths to be fashioned from a few modular sections, curves to follow a desired installation contour, and reduces the need for multiple curtain airbag inflators.
In one embodiment, the modular curtain airbag inflator includes at least two inflator sections. Preferably, the inflator sections comprise rigid metal cylindrical casings. The inflator sections contain gas generant disposed within an internal gas passage way. A first inflator section is connected to a gas generant initiator at one end. The first inflator section is connected to a first connector at the other end. The first connector is connected to a flexible hose which is connected to an end of a second inflator section by a second connector. The second section is connected to a stop that seals off the internal gas passage way.
The flexible hose and connectors continue the internal gas passage way such that inflation gas generated in the first inflator section may travel through the internal gas passage way to the second inflator section. Within the second inflator section, the inflation gas ignites gas generant to create more inflation gas and continues traveling down the internal gas passage way of the second inflator section.
In an alternative embodiment, the modular airbag inflator includes a supplemental inflator attached to an end opposite the end attached to an initiator. The modular airbag inflator is configured to initiate the supplemental inflator subsequent to igniting gas generant within previous inflator sections. The supplemental inflator is configured to add inflation gas to a curtain airbag such that a desirable inflation level is maintained over an extended period.
These and other features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.